2 * moves.c - Move generation and checking
4 * Copyright 1991 by Digital Equipment Corporation, Maynard,
7 * Enhancements Copyright 1992-2001, 2002, 2003, 2004, 2005, 2006,
8 * 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
10 * Enhancements Copyright 2005 Alessandro Scotti
12 * The following terms apply to Digital Equipment Corporation's copyright
14 * ------------------------------------------------------------------------
17 * Permission to use, copy, modify, and distribute this software and its
18 * documentation for any purpose and without fee is hereby granted,
19 * provided that the above copyright notice appear in all copies and that
20 * both that copyright notice and this permission notice appear in
21 * supporting documentation, and that the name of Digital not be
22 * used in advertising or publicity pertaining to distribution of the
23 * software without specific, written prior permission.
25 * DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
26 * ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
27 * DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
28 * ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
29 * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
30 * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
32 * ------------------------------------------------------------------------
34 * The following terms apply to the enhanced version of XBoard
35 * distributed by the Free Software Foundation:
36 * ------------------------------------------------------------------------
38 * GNU XBoard is free software: you can redistribute it and/or modify
39 * it under the terms of the GNU General Public License as published by
40 * the Free Software Foundation, either version 3 of the License, or (at
41 * your option) any later version.
43 * GNU XBoard is distributed in the hope that it will be useful, but
44 * WITHOUT ANY WARRANTY; without even the implied warranty of
45 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
46 * General Public License for more details.
48 * You should have received a copy of the GNU General Public License
49 * along with this program. If not, see http://www.gnu.org/licenses/. *
51 *------------------------------------------------------------------------
52 ** See the file ChangeLog for a revision history. */
59 #else /* not HAVE_STRING_H */
61 #endif /* not HAVE_STRING_H */
67 int WhitePiece P((ChessSquare));
68 int BlackPiece P((ChessSquare));
69 int SameColor P((ChessSquare, ChessSquare));
70 int PosFlags(int index);
72 extern signed char initialRights[BOARD_FILES]; /* [HGM] all rights enabled, set in InitPosition */
78 return (int) piece >= (int) WhitePawn && (int) piece < (int) BlackPawn;
84 return (int) piece >= (int) BlackPawn && (int) piece < (int) EmptySquare;
87 int SameColor(piece1, piece2)
88 ChessSquare piece1, piece2;
90 return ((int) piece1 >= (int) WhitePawn && /* [HGM] can be > King ! */
91 (int) piece1 < (int) BlackPawn &&
92 (int) piece2 >= (int) WhitePawn &&
93 (int) piece2 < (int) BlackPawn)
94 || ((int) piece1 >= (int) BlackPawn &&
95 (int) piece1 < (int) EmptySquare &&
96 (int) piece2 >= (int) BlackPawn &&
97 (int) piece2 < (int) EmptySquare);
100 char pieceToChar[] = {
101 'P', 'N', 'B', 'R', 'Q', 'F', 'E', 'A', 'C', 'W', 'M',
102 'O', 'H', 'I', 'J', 'G', 'D', 'V', 'L', 'S', 'U', 'K',
103 'p', 'n', 'b', 'r', 'q', 'f', 'e', 'a', 'c', 'w', 'm',
104 'o', 'h', 'i', 'j', 'g', 'd', 'v', 'l', 's', 'u', 'k',
106 char pieceNickName[EmptySquare];
111 if((int)p < 0 || (int)p >= (int)EmptySquare) return('x'); /* [HGM] for safety */
112 return pieceToChar[(int) p];
115 int PieceToNumber(p) /* [HGM] holdings: count piece type, ignoring non-participating piece types */
119 ChessSquare start = (int)p >= (int)BlackPawn ? BlackPawn : WhitePawn;
121 while(start++ != p) if(pieceToChar[(int)start-1] != '.') i++;
125 ChessSquare CharToPiece(c)
129 for(i=0; i< (int) EmptySquare; i++)
130 if(pieceNickName[i] == c) return (ChessSquare) i;
131 for(i=0; i< (int) EmptySquare; i++)
132 if(pieceToChar[i] == c) return (ChessSquare) i;
136 void CopyBoard(to, from)
141 for (i = 0; i < BOARD_HEIGHT; i++)
142 for (j = 0; j < BOARD_WIDTH; j++)
143 to[i][j] = from[i][j];
144 for (j = 0; j < BOARD_FILES-1; j++) // [HGM] gamestate: copy castling rights and ep status
145 to[CASTLING][j] = from[CASTLING][j];
146 to[HOLDINGS_SET] = 0; // flag used in ICS play
149 int CompareBoards(board1, board2)
150 Board board1, board2;
154 for (i = 0; i < BOARD_HEIGHT; i++)
155 for (j = 0; j < BOARD_WIDTH; j++) {
156 if (board1[i][j] != board2[i][j])
163 /* Call callback once for each pseudo-legal move in the given
164 position, except castling moves. A move is pseudo-legal if it is
165 legal, or if it would be legal except that it leaves the king in
166 check. In the arguments, epfile is EP_NONE if the previous move
167 was not a double pawn push, or the file 0..7 if it was, or
168 EP_UNKNOWN if we don't know and want to allow all e.p. captures.
169 Promotion moves generated are to Queen only.
171 void GenPseudoLegal(board, flags, callback, closure)
174 MoveCallback callback;
178 int i, j, d, s, fs, rs, rt, ft, m;
179 int epfile = (signed char)board[EP_STATUS]; // [HGM] gamestate: extract ep status from board
180 int promoRank = gameInfo.variant == VariantMakruk ? 3 : 1;
182 for (rf = 0; rf < BOARD_HEIGHT; rf++)
183 for (ff = BOARD_LEFT; ff < BOARD_RGHT; ff++) {
186 if (flags & F_WHITE_ON_MOVE) {
187 if (!WhitePiece(board[rf][ff])) continue;
189 if (!BlackPiece(board[rf][ff])) continue;
191 m = 0; piece = board[rf][ff];
192 if(PieceToChar(piece) == '~')
193 piece = (ChessSquare) ( DEMOTED piece );
194 if(gameInfo.variant == VariantShogi)
195 piece = (ChessSquare) ( SHOGI piece );
198 /* case EmptySquare: [HGM] this is nonsense, and conflicts with Shogi cases */
200 /* can't happen ([HGM] except for faries...) */
204 if(gameInfo.variant == VariantXiangqi) {
205 /* [HGM] capture and move straight ahead in Xiangqi */
206 if (rf < BOARD_HEIGHT-1 &&
207 !SameColor(board[rf][ff], board[rf + 1][ff]) ) {
208 callback(board, flags, NormalMove,
209 rf, ff, rf + 1, ff, closure);
211 /* and move sideways when across the river */
212 for (s = -1; s <= 1; s += 2) {
213 if (rf >= BOARD_HEIGHT>>1 &&
214 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
215 !WhitePiece(board[rf][ff+s]) ) {
216 callback(board, flags, NormalMove,
217 rf, ff, rf, ff+s, closure);
222 if (rf < BOARD_HEIGHT-1 && board[rf + 1][ff] == EmptySquare) {
223 callback(board, flags,
224 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
225 rf, ff, rf + 1, ff, closure);
227 if (rf == 1 && board[2][ff] == EmptySquare &&
228 gameInfo.variant != VariantShatranj && /* [HGM] */
229 gameInfo.variant != VariantCourier && /* [HGM] */
230 board[3][ff] == EmptySquare ) {
231 callback(board, flags, NormalMove,
232 rf, ff, 3, ff, closure);
234 for (s = -1; s <= 1; s += 2) {
235 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
236 ((flags & F_KRIEGSPIEL_CAPTURE) ||
237 BlackPiece(board[rf + 1][ff + s]))) {
238 callback(board, flags,
239 rf >= BOARD_HEIGHT-1-promoRank ? WhitePromotion : NormalMove,
240 rf, ff, rf + 1, ff + s, closure);
242 if (rf == BOARD_HEIGHT-4) {
243 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
244 (epfile == ff + s || epfile == EP_UNKNOWN) &&
245 board[BOARD_HEIGHT-4][ff + s] == BlackPawn &&
246 board[BOARD_HEIGHT-3][ff + s] == EmptySquare) {
247 callback(board, flags, WhiteCapturesEnPassant,
248 rf, ff, 5, ff + s, closure);
255 if(gameInfo.variant == VariantXiangqi) {
256 /* [HGM] capture straight ahead in Xiangqi */
257 if (rf > 0 && !SameColor(board[rf][ff], board[rf - 1][ff]) ) {
258 callback(board, flags, NormalMove,
259 rf, ff, rf - 1, ff, closure);
261 /* and move sideways when across the river */
262 for (s = -1; s <= 1; s += 2) {
263 if (rf < BOARD_HEIGHT>>1 &&
264 ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
265 !BlackPiece(board[rf][ff+s]) ) {
266 callback(board, flags, NormalMove,
267 rf, ff, rf, ff+s, closure);
272 if (rf > 0 && board[rf - 1][ff] == EmptySquare) {
273 callback(board, flags,
274 rf <= promoRank ? BlackPromotion : NormalMove,
275 rf, ff, rf - 1, ff, closure);
277 if (rf == BOARD_HEIGHT-2 && board[BOARD_HEIGHT-3][ff] == EmptySquare &&
278 gameInfo.variant != VariantShatranj && /* [HGM] */
279 gameInfo.variant != VariantCourier && /* [HGM] */
280 board[BOARD_HEIGHT-4][ff] == EmptySquare) {
281 callback(board, flags, NormalMove,
282 rf, ff, BOARD_HEIGHT-4, ff, closure);
284 for (s = -1; s <= 1; s += 2) {
285 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
286 ((flags & F_KRIEGSPIEL_CAPTURE) ||
287 WhitePiece(board[rf - 1][ff + s]))) {
288 callback(board, flags,
289 rf <= promoRank ? BlackPromotion : NormalMove,
290 rf, ff, rf - 1, ff + s, closure);
293 if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
294 (epfile == ff + s || epfile == EP_UNKNOWN) &&
295 board[3][ff + s] == WhitePawn &&
296 board[2][ff + s] == EmptySquare) {
297 callback(board, flags, BlackCapturesEnPassant,
298 rf, ff, 2, ff + s, closure);
309 for (i = -1; i <= 1; i += 2)
310 for (j = -1; j <= 1; j += 2)
311 for (s = 1; s <= 2; s++) {
314 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
315 && ( gameInfo.variant != VariantXiangqi || board[rf+i*(s-1)][ff+j*(2-s)] == EmptySquare)
316 && !SameColor(board[rf][ff], board[rt][ft]))
317 callback(board, flags, NormalMove,
318 rf, ff, rt, ft, closure);
322 case SHOGI WhiteKnight:
323 for (s = -1; s <= 1; s += 2) {
324 if (rf < BOARD_HEIGHT-2 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
325 !SameColor(board[rf][ff], board[rf + 2][ff + s])) {
326 callback(board, flags, NormalMove,
327 rf, ff, rf + 2, ff + s, closure);
332 case SHOGI BlackKnight:
333 for (s = -1; s <= 1; s += 2) {
334 if (rf > 1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
335 !SameColor(board[rf][ff], board[rf - 2][ff + s])) {
336 callback(board, flags, NormalMove,
337 rf, ff, rf - 2, ff + s, closure);
344 for (d = 0; d <= 1; d++)
345 for (s = -1; s <= 1; s += 2) {
348 rt = rf + (i * s) * d;
349 ft = ff + (i * s) * (1 - d);
350 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
351 if (m == 0 && board[rt][ft] == EmptySquare)
352 callback(board, flags, NormalMove,
353 rf, ff, rt, ft, closure);
354 if (m == 1 && board[rt][ft] != EmptySquare &&
355 !SameColor(board[rf][ff], board[rt][ft]) )
356 callback(board, flags, NormalMove,
357 rf, ff, rt, ft, closure);
358 if (board[rt][ft] != EmptySquare && m++) break;
363 /* Gold General (and all its promoted versions) . First do the */
364 /* diagonal forward steps, then proceed as normal Wazir */
365 case SHOGI WhiteWazir:
366 case SHOGI (PROMOTED WhitePawn):
367 case SHOGI (PROMOTED WhiteKnight):
368 case SHOGI (PROMOTED WhiteQueen):
369 case SHOGI (PROMOTED WhiteFerz):
370 for (s = -1; s <= 1; s += 2) {
371 if (rf < BOARD_HEIGHT-1 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
372 !SameColor(board[rf][ff], board[rf + 1][ff + s])) {
373 callback(board, flags, NormalMove,
374 rf, ff, rf + 1, ff + s, closure);
379 case SHOGI BlackWazir:
380 case SHOGI (PROMOTED BlackPawn):
381 case SHOGI (PROMOTED BlackKnight):
382 case SHOGI (PROMOTED BlackQueen):
383 case SHOGI (PROMOTED BlackFerz):
384 for (s = -1; s <= 1; s += 2) {
385 if (rf > 0 && ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT &&
386 !SameColor(board[rf][ff], board[rf - 1][ff + s])) {
387 callback(board, flags, NormalMove,
388 rf, ff, rf - 1, ff + s, closure);
395 for (d = 0; d <= 1; d++)
396 for (s = -1; s <= 1; s += 2) {
398 ft = ff + s * (1 - d);
399 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
400 && !SameColor(board[rf][ff], board[rt][ft]) &&
401 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
402 callback(board, flags, NormalMove,
403 rf, ff, rt, ft, closure);
409 /* [HGM] support Shatranj pieces */
410 for (rs = -1; rs <= 1; rs += 2)
411 for (fs = -1; fs <= 1; fs += 2) {
414 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
415 && ( gameInfo.variant != VariantXiangqi ||
416 board[rf+rs][ff+fs] == EmptySquare && (2*rf < BOARD_HEIGHT) == (2*rt < BOARD_HEIGHT) )
418 && !SameColor(board[rf][ff], board[rt][ft]))
419 callback(board, flags, NormalMove,
420 rf, ff, rt, ft, closure);
421 if(gameInfo.variant != VariantFairy && gameInfo.variant != VariantGreat) continue;
422 rt = rf + rs; // in unknown variant we assume Modern Elephant, which can also do one step
424 if (!(rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT)
425 && !SameColor(board[rf][ff], board[rt][ft]))
426 callback(board, flags, NormalMove,
427 rf, ff, rt, ft, closure);
431 /* Shogi Dragon Horse has to continue with Wazir after Bishop */
432 case SHOGI WhiteCardinal:
433 case SHOGI BlackCardinal:
436 /* Capablanca Archbishop continues as Knight */
441 /* Shogi Bishops are ordinary Bishops */
442 case SHOGI WhiteBishop:
443 case SHOGI BlackBishop:
446 for (rs = -1; rs <= 1; rs += 2)
447 for (fs = -1; fs <= 1; fs += 2)
451 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
452 if (SameColor(board[rf][ff], board[rt][ft])) break;
453 callback(board, flags, NormalMove,
454 rf, ff, rt, ft, closure);
455 if (board[rt][ft] != EmptySquare) break;
457 if(m==1) goto mounted;
458 if(m==2) goto finishGold;
459 /* Bishop falls through */
462 /* Shogi Lance is unlike anything, and asymmetric at that */
463 case SHOGI WhiteQueen:
467 if (rt >= BOARD_HEIGHT) break;
468 if (SameColor(board[rf][ff], board[rt][ft])) break;
469 callback(board, flags, NormalMove,
470 rf, ff, rt, ft, closure);
471 if (board[rt][ft] != EmptySquare) break;
475 case SHOGI BlackQueen:
480 if (SameColor(board[rf][ff], board[rt][ft])) break;
481 callback(board, flags, NormalMove,
482 rf, ff, rt, ft, closure);
483 if (board[rt][ft] != EmptySquare) break;
487 /* Make Dragon-King Dababba & Rook-like outside Shogi, for better disambiguation in variant Fairy */
490 for (d = 0; d <= 1; d++) // Dababba moves that Rook cannot do
491 for (s = -2; s <= 2; s += 4) {
493 ft = ff + s * (1 - d);
494 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT || board[rf+rt>>1][ff+ft>>1] == EmptySquare) continue;
495 if (SameColor(board[rf][ff], board[rt][ft])) continue;
496 callback(board, flags, NormalMove, rf, ff, rt, ft, closure);
500 /* Shogi Dragon King has to continue as Ferz after Rook moves */
501 case SHOGI WhiteDragon:
502 case SHOGI BlackDragon:
505 /* Capablanca Chancellor sets flag to continue as Knight */
510 /* Shogi Rooks are ordinary Rooks */
511 case SHOGI WhiteRook:
512 case SHOGI BlackRook:
516 for (d = 0; d <= 1; d++)
517 for (s = -1; s <= 1; s += 2)
519 rt = rf + (i * s) * d;
520 ft = ff + (i * s) * (1 - d);
521 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
522 if (SameColor(board[rf][ff], board[rt][ft])) break;
523 callback(board, flags, NormalMove,
524 rf, ff, rt, ft, closure);
525 if (board[rt][ft] != EmptySquare) break;
527 if(m==1) goto mounted;
528 if(m==2) goto finishSilver;
533 for (rs = -1; rs <= 1; rs++)
534 for (fs = -1; fs <= 1; fs++) {
535 if (rs == 0 && fs == 0) continue;
539 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
540 if (SameColor(board[rf][ff], board[rt][ft])) break;
541 callback(board, flags, NormalMove,
542 rf, ff, rt, ft, closure);
543 if (board[rt][ft] != EmptySquare) break;
548 /* Shogi Pawn and Silver General: first the Pawn move, */
549 /* then the General continues like a Ferz */
551 if(gameInfo.variant != VariantMakruk) goto commoner;
552 case SHOGI WhitePawn:
553 case SHOGI WhiteFerz:
554 if (rf < BOARD_HEIGHT-1 &&
555 !SameColor(board[rf][ff], board[rf + 1][ff]) )
556 callback(board, flags, NormalMove,
557 rf, ff, rf + 1, ff, closure);
558 if(piece != SHOGI WhitePawn) goto finishSilver;
562 if(gameInfo.variant != VariantMakruk) goto commoner;
563 case SHOGI BlackPawn:
564 case SHOGI BlackFerz:
566 !SameColor(board[rf][ff], board[rf - 1][ff]) )
567 callback(board, flags, NormalMove,
568 rf, ff, rf - 1, ff, closure);
569 if(piece == SHOGI BlackPawn) break;
574 /* [HGM] support Shatranj pieces */
575 for (rs = -1; rs <= 1; rs += 2)
576 for (fs = -1; fs <= 1; fs += 2) {
579 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
580 if (!SameColor(board[rf][ff], board[rt][ft]) &&
581 (gameInfo.variant != VariantXiangqi || InPalace(rt, ft) ) )
582 callback(board, flags, NormalMove,
583 rf, ff, rt, ft, closure);
589 m++; // [HGM] superchess: use for Centaur
591 case SHOGI WhiteKing:
592 case SHOGI BlackKing:
596 for (i = -1; i <= 1; i++)
597 for (j = -1; j <= 1; j++) {
598 if (i == 0 && j == 0) continue;
601 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) continue;
602 if (SameColor(board[rf][ff], board[rt][ft])) continue;
603 callback(board, flags, NormalMove,
604 rf, ff, rt, ft, closure);
606 if(m==1) goto mounted;
609 case WhiteNightrider:
610 case BlackNightrider:
611 for (i = -1; i <= 1; i += 2)
612 for (j = -1; j <= 1; j += 2)
613 for (s = 1; s <= 2; s++) { int k;
617 if (rt < 0 || rt >= BOARD_HEIGHT || ft < BOARD_LEFT || ft >= BOARD_RGHT) break;
618 if (SameColor(board[rf][ff], board[rt][ft])) break;
619 callback(board, flags, NormalMove,
620 rf, ff, rt, ft, closure);
621 if (board[rt][ft] != EmptySquare) break;
625 case WhiteFalcon: // [HGM] wild: for wildcards, self-capture symbolizes move to anywhere
631 callback(board, flags, NormalMove, rf, ff, rf, ff, closure);
644 extern void GenLegalCallback P((Board board, int flags, ChessMove kind,
645 int rf, int ff, int rt, int ft,
648 void GenLegalCallback(board, flags, kind, rf, ff, rt, ft, closure)
655 register GenLegalClosure *cl = (GenLegalClosure *) closure;
657 if (!(flags & F_IGNORE_CHECK) &&
658 CheckTest(board, flags, rf, ff, rt, ft,
659 kind == WhiteCapturesEnPassant ||
660 kind == BlackCapturesEnPassant)) return;
661 if (flags & F_ATOMIC_CAPTURE) {
662 if (board[rt][ft] != EmptySquare ||
663 kind == WhiteCapturesEnPassant || kind == BlackCapturesEnPassant) {
665 ChessSquare king = (flags & F_WHITE_ON_MOVE) ? WhiteKing : BlackKing;
666 if (board[rf][ff] == king) return;
667 for (r = rt-1; r <= rt+1; r++) {
668 for (f = ft-1; f <= ft+1; f++) {
669 if (r >= 0 && r < BOARD_HEIGHT && f >= BOARD_LEFT && f < BOARD_RGHT &&
670 board[r][f] == king) return;
675 cl->cb(board, flags, kind, rf, ff, rt, ft, cl->cl);
682 int captures; // [HGM] losers
683 } LegalityTestClosure;
686 /* Like GenPseudoLegal, but (1) include castling moves, (2) unless
687 F_IGNORE_CHECK is set in the flags, omit moves that would leave the
688 king in check, and (3) if F_ATOMIC_CAPTURE is set in the flags, omit
689 moves that would destroy your own king. The CASTLE_OK flags are
690 true if castling is not yet ruled out by a move of the king or
691 rook. Return TRUE if the player on move is currently in check and
692 F_IGNORE_CHECK is not set. [HGM] add castlingRights parameter */
693 int GenLegal(board, flags, callback, closure)
696 MoveCallback callback;
700 int ff, ft, k, left, right;
701 int ignoreCheck = (flags & F_IGNORE_CHECK) != 0;
702 ChessSquare wKing = WhiteKing, bKing = BlackKing, *castlingRights = board[CASTLING];
706 GenPseudoLegal(board, flags, GenLegalCallback, (VOIDSTAR) &cl);
709 CheckTest(board, flags, -1, -1, -1, -1, FALSE)) return TRUE;
711 /* Generate castling moves */
712 if(gameInfo.variant == VariantKnightmate) { /* [HGM] Knightmate */
713 wKing = WhiteUnicorn; bKing = BlackUnicorn;
716 for (ff = BOARD_WIDTH>>1; ff >= (BOARD_WIDTH-1)>>1; ff-- /*ics wild 1*/) {
717 if ((flags & F_WHITE_ON_MOVE) &&
718 (flags & F_WHITE_KCASTLE_OK) &&
719 board[0][ff] == wKing &&
720 board[0][ff + 1] == EmptySquare &&
721 board[0][ff + 2] == EmptySquare &&
722 board[0][BOARD_RGHT-3] == EmptySquare &&
723 board[0][BOARD_RGHT-2] == EmptySquare &&
724 board[0][BOARD_RGHT-1] == WhiteRook &&
725 castlingRights[0] != NoRights && /* [HGM] check rights */
726 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
728 (!CheckTest(board, flags, 0, ff, 0, ff + 1, FALSE) &&
729 !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-3, FALSE) &&
730 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, 0, ff, 0, BOARD_RGHT-2, FALSE)) &&
731 !CheckTest(board, flags, 0, ff, 0, ff + 2, FALSE)))) {
733 callback(board, flags,
734 ff==BOARD_WIDTH>>1 ? WhiteKingSideCastle : WhiteKingSideCastleWild,
735 0, ff, 0, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
737 if ((flags & F_WHITE_ON_MOVE) &&
738 (flags & F_WHITE_QCASTLE_OK) &&
739 board[0][ff] == wKing &&
740 board[0][ff - 1] == EmptySquare &&
741 board[0][ff - 2] == EmptySquare &&
742 board[0][BOARD_LEFT+2] == EmptySquare &&
743 board[0][BOARD_LEFT+1] == EmptySquare &&
744 board[0][BOARD_LEFT+0] == WhiteRook &&
745 castlingRights[1] != NoRights && /* [HGM] check rights */
746 ( castlingRights[2] == ff || castlingRights[6] == ff ) &&
748 (!CheckTest(board, flags, 0, ff, 0, ff - 1, FALSE) &&
749 !CheckTest(board, flags, 0, ff, 0, BOARD_LEFT+3, FALSE) &&
750 !CheckTest(board, flags, 0, ff, 0, ff - 2, FALSE)))) {
752 callback(board, flags,
753 ff==BOARD_WIDTH>>1 ? WhiteQueenSideCastle : WhiteQueenSideCastleWild,
754 0, ff, 0, ff - ((gameInfo.boardWidth+2)>>2), closure);
756 if (!(flags & F_WHITE_ON_MOVE) &&
757 (flags & F_BLACK_KCASTLE_OK) &&
758 board[BOARD_HEIGHT-1][ff] == bKing &&
759 board[BOARD_HEIGHT-1][ff + 1] == EmptySquare &&
760 board[BOARD_HEIGHT-1][ff + 2] == EmptySquare &&
761 board[BOARD_HEIGHT-1][BOARD_RGHT-3] == EmptySquare &&
762 board[BOARD_HEIGHT-1][BOARD_RGHT-2] == EmptySquare &&
763 board[BOARD_HEIGHT-1][BOARD_RGHT-1] == BlackRook &&
764 castlingRights[3] != NoRights && /* [HGM] check rights */
765 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
767 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 1, FALSE) &&
768 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-3, FALSE) &&
769 (gameInfo.variant != VariantJanus || !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_RGHT-2, FALSE)) &&
770 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + 2, FALSE)))) {
772 callback(board, flags,
773 ff==BOARD_WIDTH>>1 ? BlackKingSideCastle : BlackKingSideCastleWild,
774 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff + ((gameInfo.boardWidth+2)>>2) + (gameInfo.variant == VariantJanus), closure);
776 if (!(flags & F_WHITE_ON_MOVE) &&
777 (flags & F_BLACK_QCASTLE_OK) &&
778 board[BOARD_HEIGHT-1][ff] == bKing &&
779 board[BOARD_HEIGHT-1][ff - 1] == EmptySquare &&
780 board[BOARD_HEIGHT-1][ff - 2] == EmptySquare &&
781 board[BOARD_HEIGHT-1][BOARD_LEFT+2] == EmptySquare &&
782 board[BOARD_HEIGHT-1][BOARD_LEFT+1] == EmptySquare &&
783 board[BOARD_HEIGHT-1][BOARD_LEFT+0] == BlackRook &&
784 castlingRights[4] != NoRights && /* [HGM] check rights */
785 ( castlingRights[5] == ff || castlingRights[7] == ff ) &&
787 (!CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 1, FALSE) &&
788 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, BOARD_LEFT+3, FALSE) &&
789 !CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - 2, FALSE)))) {
791 callback(board, flags,
792 ff==BOARD_WIDTH>>1 ? BlackQueenSideCastle : BlackQueenSideCastleWild,
793 BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ff - ((gameInfo.boardWidth+2)>>2), closure);
797 if(flags & F_FRC_TYPE_CASTLING) {
799 /* generate all potential FRC castling moves (KxR), ignoring flags */
800 /* [HGM] test if the Rooks we find have castling rights */
803 if ((flags & F_WHITE_ON_MOVE) != 0) {
804 ff = castlingRights[2]; /* King file if we have any rights */
805 if(ff != NoRights && board[0][ff] == WhiteKing) {
806 if (appData.debugMode) {
807 fprintf(debugFP, "FRC castling, %d %d %d %d %d %d\n",
808 castlingRights[0],castlingRights[1],ff,castlingRights[3],castlingRights[4],castlingRights[5]);
810 ft = castlingRights[0]; /* Rook file if we have H-side rights */
812 right = BOARD_RGHT-2;
813 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
814 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
815 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
816 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
817 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
818 if(ft != NoRights && board[0][ft] == WhiteRook)
819 callback(board, flags, WhiteHSideCastleFR, 0, ff, 0, ft, closure);
821 ft = castlingRights[1]; /* Rook file if we have A-side rights */
824 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
825 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
826 if(k != ft && board[0][k] != EmptySquare) ft = NoRights;
827 if(ff > BOARD_LEFT+2)
828 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
829 if(!ignoreCheck && CheckTest(board, flags, 0, ff, 0, k, FALSE)) ft = NoRights;
830 if(ft != NoRights && board[0][ft] == WhiteRook)
831 callback(board, flags, WhiteASideCastleFR, 0, ff, 0, ft, closure);
834 ff = castlingRights[5]; /* King file if we have any rights */
835 if(ff != NoRights && board[BOARD_HEIGHT-1][ff] == BlackKing) {
836 ft = castlingRights[3]; /* Rook file if we have H-side rights */
838 right = BOARD_RGHT-2;
839 if(ff == BOARD_RGHT-2) left = right = ff-1; /* special case */
840 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
841 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
842 for(k=left; k<right && ft != NoRights; k++) /* then if not checked */
843 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
844 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
845 callback(board, flags, BlackHSideCastleFR, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ft, closure);
847 ft = castlingRights[4]; /* Rook file if we have A-side rights */
850 if(ff <= BOARD_LEFT+2) { left = ff+1; right = BOARD_LEFT+3; }
851 for(k=left; k<=right && ft != NoRights; k++) /* first test if blocked */
852 if(k != ft && board[BOARD_HEIGHT-1][k] != EmptySquare) ft = NoRights;
853 if(ff > BOARD_LEFT+2)
854 for(k=left+1; k<=right && ft != NoRights; k++) /* then if not checked */
855 if(!ignoreCheck && CheckTest(board, flags, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, k, FALSE)) ft = NoRights;
856 if(ft != NoRights && board[BOARD_HEIGHT-1][ft] == BlackRook)
857 callback(board, flags, BlackASideCastleFR, BOARD_HEIGHT-1, ff, BOARD_HEIGHT-1, ft, closure);
873 extern void CheckTestCallback P((Board board, int flags, ChessMove kind,
874 int rf, int ff, int rt, int ft,
878 void CheckTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
885 register CheckTestClosure *cl = (CheckTestClosure *) closure;
887 if (rt == cl->rking && ft == cl->fking) cl->check++;
891 /* If the player on move were to move from (rf, ff) to (rt, ft), would
892 he leave himself in check? Or if rf == -1, is the player on move
893 in check now? enPassant must be TRUE if the indicated move is an
894 e.p. capture. The possibility of castling out of a check along the
895 back rank is not accounted for (i.e., we still return nonzero), as
896 this is illegal anyway. Return value is the number of times the
898 int CheckTest(board, flags, rf, ff, rt, ft, enPassant)
901 int rf, ff, rt, ft, enPassant;
904 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
905 ChessSquare captured = EmptySquare;
906 /* Suppress warnings on uninitialized variables */
908 if(gameInfo.variant == VariantXiangqi)
909 king = flags & F_WHITE_ON_MOVE ? WhiteWazir : BlackWazir;
910 if(gameInfo.variant == VariantKnightmate)
911 king = flags & F_WHITE_ON_MOVE ? WhiteUnicorn : BlackUnicorn;
915 captured = board[rf][ft];
916 board[rf][ft] = EmptySquare;
918 captured = board[rt][ft];
920 board[rt][ft] = board[rf][ff];
921 board[rf][ff] = EmptySquare;
922 } else board[rt][ft] = ff; // [HGM] drop
924 /* For compatibility with ICS wild 9, we scan the board in the
925 order a1, a2, a3, ... b1, b2, ..., h8 to find the first king,
926 and we test only whether that one is in check. */
928 for (cl.fking = BOARD_LEFT+0; cl.fking < BOARD_RGHT; cl.fking++)
929 for (cl.rking = 0; cl.rking < BOARD_HEIGHT; cl.rking++) {
930 if (board[cl.rking][cl.fking] == king) {
931 if(gameInfo.variant == VariantXiangqi) {
932 /* [HGM] In Xiangqi opposing Kings means check as well */
934 dir = (king >= BlackPawn) ? -1 : 1;
935 for( i=cl.rking+dir; i>=0 && i<BOARD_HEIGHT &&
936 board[i][cl.fking] == EmptySquare; i+=dir );
937 if(i>=0 && i<BOARD_HEIGHT &&
938 board[i][cl.fking] == (dir>0 ? BlackWazir : WhiteWazir) )
942 GenPseudoLegal(board, flags ^ F_WHITE_ON_MOVE, CheckTestCallback, (VOIDSTAR) &cl);
943 goto undo_move; /* 2-level break */
950 board[rf][ff] = board[rt][ft];
952 board[rf][ft] = captured;
953 board[rt][ft] = EmptySquare;
955 board[rt][ft] = captured;
957 } else board[rt][ft] = EmptySquare; // [HGM] drop
959 return cl.fking < BOARD_RGHT ? cl.check : 1000; // [HGM] atomic: return 1000 if we have no king
962 ChessMove LegalDrop(board, flags, piece, rt, ft)
967 { // [HGM] put drop legality testing in separate routine for clarity
969 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
970 if(board[rt][ft] != EmptySquare) return ImpossibleMove; // must drop to empty square
971 n = PieceToNumber(piece);
972 if(gameInfo.holdingsWidth == 0 || (flags & F_WHITE_ON_MOVE ? board[n][BOARD_WIDTH-1] : board[BOARD_HEIGHT-1-n][0]) != piece)
973 return ImpossibleMove; // piece not available
974 if(gameInfo.variant == VariantShogi) { // in Shogi lots of drops are forbidden!
975 if((piece == WhitePawn || piece == WhiteQueen) && rt == BOARD_HEIGHT-1 ||
976 (piece == BlackPawn || piece == BlackQueen) && rt == 0 ||
977 piece == WhiteKnight && rt > BOARD_HEIGHT-3 ||
978 piece == BlackKnight && rt < 2 ) return IllegalMove; // e.g. where dropped piece has no moves
979 if(piece == WhitePawn || piece == BlackPawn) {
981 for(r=1; r<BOARD_HEIGHT-1; r++)
982 if(board[r][ft] == piece) return IllegalMove; // or there already is a Pawn in file
983 // should still test if we mate with this Pawn
986 if( (piece == WhitePawn || piece == BlackPawn) &&
987 (rt == 0 || rt == BOARD_HEIGHT -1 ) )
988 return IllegalMove; /* no pawn drops on 1st/8th */
990 if(appData.debugMode) fprintf(debugFP, "LegalDrop: %d @ %d,%d)\n", piece, ft, rt);
991 if (!(flags & F_IGNORE_CHECK) &&
992 CheckTest(board, flags, DROP_RANK, piece, rt, ft, FALSE) ) return IllegalMove;
993 return flags & F_WHITE_ON_MOVE ? WhiteDrop : BlackDrop;
996 extern void LegalityTestCallback P((Board board, int flags, ChessMove kind,
997 int rf, int ff, int rt, int ft,
1000 void LegalityTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1007 register LegalityTestClosure *cl = (LegalityTestClosure *) closure;
1009 // if (appData.debugMode) {
1010 // fprintf(debugFP, "Legality test: %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1012 if(board[rt][ft] != EmptySquare || kind==WhiteCapturesEnPassant || kind==BlackCapturesEnPassant)
1013 cl->captures++; // [HGM] losers: count legal captures
1014 if (rf == cl->rf && ff == cl->ff && rt == cl->rt && ft == cl->ft)
1018 ChessMove LegalityTest(board, flags, rf, ff, rt, ft, promoChar)
1021 int rf, ff, rt, ft, promoChar;
1023 LegalityTestClosure cl; ChessSquare piece, *castlingRights = board[CASTLING];
1025 if(rf == DROP_RANK) return LegalDrop(board, flags, ff, rt, ft);
1026 piece = board[rf][ff];
1028 if (appData.debugMode) {
1030 for(i=0; i<6; i++) fprintf(debugFP, "%d ", castlingRights[i]);
1031 fprintf(debugFP, "Legality test? %c%c%c%c\n", ff+AAA, rf+ONE, ft+AAA, rt+ONE);
1033 /* [HGM] Lance, Cobra and Falcon are wildcard pieces; consider all their moves legal */
1034 /* (perhaps we should disallow moves that obviously leave us in check?) */
1035 if(piece == WhiteFalcon || piece == BlackFalcon ||
1036 piece == WhiteCobra || piece == BlackCobra ||
1037 piece == WhiteLance || piece == BlackLance)
1038 return CheckTest(board, flags, rf, ff, rt, ft, FALSE) ? IllegalMove : NormalMove;
1044 cl.kind = IllegalMove;
1045 cl.captures = 0; // [HGM] losers: prepare to count legal captures.
1046 GenLegal(board, flags, LegalityTestCallback, (VOIDSTAR) &cl);
1047 if((flags & F_MANDATORY_CAPTURE) && cl.captures && board[rt][ft] == EmptySquare
1048 && cl.kind != WhiteCapturesEnPassant && cl.kind != BlackCapturesEnPassant)
1049 return(IllegalMove); // [HGM] losers: if there are legal captures, non-capts are illegal
1051 if(promoChar == 'x') promoChar = NULLCHAR; // [HGM] is this ever the case?
1052 if(gameInfo.variant == VariantShogi) {
1053 /* [HGM] Shogi promotions. '=' means defer */
1054 if(rf != DROP_RANK && cl.kind == NormalMove) {
1055 ChessSquare piece = board[rf][ff];
1057 if(promoChar == PieceToChar(BlackQueen)) promoChar = NULLCHAR; /* [HGM] Kludge */
1058 if(promoChar == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1059 promoChar == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1060 promoChar == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1061 promoChar = '+'; // allowed ICS notations
1062 if(appData.debugMode)fprintf(debugFP,"SHOGI promoChar = %c\n", promoChar ? promoChar : '-');
1063 if(promoChar != NULLCHAR && promoChar != '+' && promoChar != '=')
1064 return CharToPiece(promoChar) == EmptySquare ? ImpossibleMove : IllegalMove;
1065 else if(flags & F_WHITE_ON_MOVE) {
1066 if( (int) piece < (int) WhiteWazir &&
1067 (rf >= BOARD_HEIGHT*2/3 || rt >= BOARD_HEIGHT*2/3) ) {
1068 if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
1069 piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
1070 cl.kind = promoChar == '=' ? IllegalMove : WhitePromotion;
1071 else /* promotion optional, default is defer */
1072 cl.kind = promoChar == '+' ? WhitePromotion : WhiteNonPromotion;
1073 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1075 if( (int) piece < (int) BlackWazir && (rf < BOARD_HEIGHT/3 || rt < BOARD_HEIGHT/3) ) {
1076 if( (piece == BlackPawn || piece == BlackQueen) && rt < 1 ||
1077 piece == BlackKnight && rt < 2 ) /* promotion obligatory */
1078 cl.kind = promoChar == '=' ? IllegalMove : BlackPromotion;
1079 else /* promotion optional, default is defer */
1080 cl.kind = promoChar == '+' ? BlackPromotion : BlackNonPromotion;
1081 } else cl.kind = promoChar == '+' ? IllegalMove : NormalMove;
1085 if (promoChar != NULLCHAR) {
1086 if(promoChar == '=') cl.kind = IllegalMove; else // [HGM] shogi: no deferred promotion outside Shogi
1087 if (cl.kind == WhitePromotion || cl.kind == BlackPromotion) {
1088 if(CharToPiece(promoChar) == EmptySquare) cl.kind = ImpossibleMove; // non-existing piece
1090 cl.kind = IllegalMove;
1100 extern void MateTestCallback P((Board board, int flags, ChessMove kind,
1101 int rf, int ff, int rt, int ft,
1104 void MateTestCallback(board, flags, kind, rf, ff, rt, ft, closure)
1111 register MateTestClosure *cl = (MateTestClosure *) closure;
1116 /* Return MT_NONE, MT_CHECK, MT_CHECKMATE, or MT_STALEMATE */
1117 int MateTest(board, flags)
1122 int inCheck, r, f, myPieces=0, hisPieces=0, nrKing=0;
1123 ChessSquare king = flags & F_WHITE_ON_MOVE ? WhiteKing : BlackKing;
1125 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) {
1126 // [HGM] losers: Count pieces and kings, to detect other unorthodox winning conditions
1127 nrKing += (board[r][f] == king); // stm has king
1128 if( board[r][f] != EmptySquare ) {
1129 if((int)board[r][f] <= (int)king && (int)board[r][f] >= (int)king - (int)WhiteKing + (int)WhitePawn)
1134 if(appData.debugMode) fprintf(debugFP, "MateTest: K=%d, my=%d, his=%d\n", nrKing, myPieces, hisPieces);
1135 switch(gameInfo.variant) { // [HGM] losers: extinction wins
1136 case VariantShatranj:
1137 if(hisPieces == 1) return myPieces > 1 ? MT_BARE : MT_DRAW;
1141 if(nrKing == 0) return MT_NOKING;
1144 if(myPieces == 1) return MT_BARE;
1147 inCheck = GenLegal(board, flags, MateTestCallback, (VOIDSTAR) &cl);
1148 // [HGM] 3check: yet to do!
1150 return inCheck ? MT_CHECK : MT_NONE;
1152 if(gameInfo.holdingsWidth && gameInfo.variant != VariantSuper || gameInfo.variant != VariantGreat) { // drop game
1153 int r, f, n, holdings = flags & F_WHITE_ON_MOVE ? BOARD_WIDTH-1 : 0;
1154 for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) if(board[r][f] == EmptySquare) // all empty squares
1155 for(n=0; n<BOARD_HEIGHT; n++) // all pieces in hand
1156 if(board[n][holdings] != EmptySquare) {
1157 int moveType = LegalDrop(board, flags, board[n][holdings], r, f);
1158 if(moveType == WhiteDrop || moveType == BlackDrop) return MT_CHECK; // we can resolve check by legal drop
1161 if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
1162 return myPieces == hisPieces ? MT_STALEMATE :
1163 myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
1164 else if(gameInfo.variant == VariantLosers) return inCheck ? MT_TRICKMATE : MT_STEALMATE;
1165 else if(gameInfo.variant == VariantGiveaway) return MT_STEALMATE; // no check exists, stalemated = win
1167 return inCheck ? MT_CHECKMATE
1168 : (gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShatranj) ?
1169 MT_STAINMATE : MT_STALEMATE;
1174 extern void DisambiguateCallback P((Board board, int flags, ChessMove kind,
1175 int rf, int ff, int rt, int ft,
1178 void DisambiguateCallback(board, flags, kind, rf, ff, rt, ft, closure)
1185 register DisambiguateClosure *cl = (DisambiguateClosure *) closure;
1186 int wildCard = FALSE; ChessSquare piece = board[rf][ff];
1188 // [HGM] wild: for wild-card pieces rt and rf are dummies
1189 if(piece == WhiteFalcon || piece == BlackFalcon ||
1190 piece == WhiteCobra || piece == BlackCobra ||
1191 piece == WhiteLance || piece == BlackLance)
1194 if ((cl->pieceIn == EmptySquare || cl->pieceIn == board[rf][ff]
1195 || PieceToChar(board[rf][ff]) == '~'
1196 && cl->pieceIn == (ChessSquare)(DEMOTED board[rf][ff])
1198 (cl->rfIn == -1 || cl->rfIn == rf) &&
1199 (cl->ffIn == -1 || cl->ffIn == ff) &&
1200 (cl->rtIn == -1 || cl->rtIn == rt || wildCard) &&
1201 (cl->ftIn == -1 || cl->ftIn == ft || wildCard)) {
1204 if(cl->count == 1 || board[rt][ft] != EmptySquare) {
1205 // [HGM] oneclick: if multiple moves, be sure we remember capture
1206 cl->piece = board[rf][ff];
1209 cl->rt = wildCard ? cl->rtIn : rt;
1210 cl->ft = wildCard ? cl->ftIn : ft;
1213 cl->captures += (board[cl->rt][cl->ft] != EmptySquare); // [HGM] oneclick: count captures
1217 void Disambiguate(board, flags, closure)
1220 DisambiguateClosure *closure;
1222 int illegal = 0; char c = closure->promoCharIn;
1224 closure->count = closure->captures = 0;
1225 closure->rf = closure->ff = closure->rt = closure->ft = 0;
1226 closure->kind = ImpossibleMove;
1227 if (appData.debugMode) {
1228 fprintf(debugFP, "Disambiguate in: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1229 closure->pieceIn,closure->ffIn,closure->rfIn,closure->ftIn,closure->rtIn,
1230 closure->promoCharIn, closure->promoCharIn >= ' ' ? closure->promoCharIn : '-');
1232 GenLegal(board, flags, DisambiguateCallback, (VOIDSTAR) closure);
1233 if (closure->count == 0) {
1234 /* See if it's an illegal move due to check */
1236 GenLegal(board, flags|F_IGNORE_CHECK, DisambiguateCallback, (VOIDSTAR) closure);
1237 if (closure->count == 0) {
1238 /* No, it's not even that */
1239 if (appData.debugMode) { int i, j;
1240 for(i=BOARD_HEIGHT-1; i>=0; i--) {
1241 for(j=0; j<BOARD_WIDTH; j++)
1242 fprintf(debugFP, "%3d", (int) board[i][j]);
1243 fprintf(debugFP, "\n");
1250 if (c == 'x') c = NULLCHAR; // get rid of any 'x' (which should never happen?)
1251 if(gameInfo.variant == VariantShogi) {
1252 /* [HGM] Shogi promotions. On input, '=' means defer, '+' promote. Afterwards, c is set to '+' for promotions, NULL other */
1253 if(closure->rfIn != DROP_RANK && closure->kind == NormalMove) {
1254 ChessSquare piece = closure->piece;
1255 if (c == 'd' && (piece == WhiteRook || piece == BlackRook) ||
1256 c == 'h' && (piece == WhiteBishop || piece == BlackBishop) ||
1257 c == 'g' && (piece <= WhiteFerz || piece <= BlackFerz && piece >= BlackPawn) )
1258 c = '+'; // allowed ICS notations
1259 if(c != NULLCHAR && c != '+' && c != '=') closure->kind = IllegalMove; // otherwise specifying a piece is illegal
1260 else if(flags & F_WHITE_ON_MOVE) {
1261 if( (int) piece < (int) WhiteWazir &&
1262 (closure->rf >= BOARD_HEIGHT-(BOARD_HEIGHT/3) || closure->rt >= BOARD_HEIGHT-(BOARD_HEIGHT/3)) ) {
1263 if( (piece == WhitePawn || piece == WhiteQueen) && closure->rt > BOARD_HEIGHT-2 ||
1264 piece == WhiteKnight && closure->rt > BOARD_HEIGHT-3) /* promotion mandatory */
1265 closure->kind = c == '=' ? IllegalMove : WhitePromotion;
1266 else /* promotion optional, default is defer */
1267 closure->kind = c == '+' ? WhitePromotion : WhiteNonPromotion;
1268 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1270 if( (int) piece < (int) BlackWazir && (closure->rf < BOARD_HEIGHT/3 || closure->rt < BOARD_HEIGHT/3) ) {
1271 if( (piece == BlackPawn || piece == BlackQueen) && closure->rt < 1 ||
1272 piece == BlackKnight && closure->rt < 2 ) /* promotion obligatory */
1273 closure->kind = c == '=' ? IllegalMove : BlackPromotion;
1274 else /* promotion optional, default is defer */
1275 closure->kind = c == '+' ? BlackPromotion : BlackNonPromotion;
1276 } else closure->kind = c == '+' ? IllegalMove : NormalMove;
1279 if(closure->kind == WhitePromotion || closure->kind == BlackPromotion) c = '+'; else
1280 if(closure->kind == WhiteNonPromotion || closure->kind == BlackNonPromotion) c = '=';
1282 if (closure->kind == WhitePromotion || closure->kind == BlackPromotion) {
1283 if(c == NULLCHAR) { // missing promoChar on mandatory promotion; use default for variant
1284 if(gameInfo.variant == VariantShatranj || gameInfo.variant == VariantCourier || gameInfo.variant == VariantMakruk)
1285 c = PieceToChar(BlackFerz);
1286 else if(gameInfo.variant == VariantGreat)
1287 c = PieceToChar(BlackMan);
1289 c = PieceToChar(BlackQueen);
1290 } else if(c == '=') closure->kind = IllegalMove; // no deferral outside Shogi
1291 } else if (c != NULLCHAR) closure->kind = IllegalMove;
1293 closure->promoChar = ToLower(c); // this can be NULLCHAR! Note we keep original promoChar even if illegal.
1294 if(c != '+' && c != '=' && c != NULLCHAR && CharToPiece(c) == EmptySquare)
1295 closure->kind = ImpossibleMove; // but we cannot handle non-existing piece types!
1296 if (closure->count > 1) {
1297 closure->kind = AmbiguousMove;
1300 /* Note: If more than one illegal move matches, but no legal
1301 moves, we return IllegalMove, not AmbiguousMove. Caller
1302 can look at closure->count to detect this.
1304 closure->kind = IllegalMove;
1306 if (appData.debugMode) {
1307 fprintf(debugFP, "Disambiguate out: %d(%d,%d)-(%d,%d) = %d (%c)\n",
1308 closure->piece,closure->ff,closure->rf,closure->ft,closure->rt,closure->promoChar,
1309 closure->promoChar >= ' ' ? closure->promoChar:'-');
1323 } CoordsToAlgebraicClosure;
1325 extern void CoordsToAlgebraicCallback P((Board board, int flags,
1326 ChessMove kind, int rf, int ff,
1327 int rt, int ft, VOIDSTAR closure));
1329 void CoordsToAlgebraicCallback(board, flags, kind, rf, ff, rt, ft, closure)
1336 register CoordsToAlgebraicClosure *cl =
1337 (CoordsToAlgebraicClosure *) closure;
1339 if (rt == cl->rt && ft == cl->ft &&
1340 (board[rf][ff] == cl->piece
1341 || PieceToChar(board[rf][ff]) == '~' &&
1342 (ChessSquare) (DEMOTED board[rf][ff]) == cl->piece)
1346 cl->kind = kind; /* this is the move we want */
1348 cl->file++; /* need file to rule out this move */
1352 cl->rank++; /* need rank to rule out this move */
1354 cl->either++; /* rank or file will rule out this move */
1360 /* Convert coordinates to normal algebraic notation.
1361 promoChar must be NULLCHAR or 'x' if not a promotion.
1363 ChessMove CoordsToAlgebraic(board, flags, rf, ff, rt, ft, promoChar, out)
1372 char *outp = out, c;
1373 CoordsToAlgebraicClosure cl;
1375 if (rf == DROP_RANK) {
1376 /* Bughouse piece drop */
1377 *outp++ = ToUpper(PieceToChar((ChessSquare) ff));
1382 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1384 return (flags & F_WHITE_ON_MOVE) ? WhiteDrop : BlackDrop;
1387 if (promoChar == 'x') promoChar = NULLCHAR;
1388 piece = board[rf][ff];
1389 if(PieceToChar(piece)=='~') piece = (ChessSquare)(DEMOTED piece);
1391 if (appData.debugMode)
1392 fprintf(debugFP, "CoordsToAlgebraic, piece=%d (%d,%d)-(%d,%d) %c\n", (int)piece,ff,rf,ft,rt,promoChar >= ' ' ? promoChar : '-');
1396 kind = LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1397 if (kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1398 /* Keep short notation if move is illegal only because it
1399 leaves the player in check, but still return IllegalMove */
1400 kind = LegalityTest(board, flags|F_IGNORE_CHECK, rf, ff, rt, ft, promoChar);
1401 if (kind == IllegalMove) break;
1406 if (ff == ft && board[rt][ft] == EmptySquare) { /* [HGM] Xiangqi has straight noncapts! */
1407 /* Non-capture; use style "e5" */
1410 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1412 /* Capture; use style "exd5" */
1413 if(gameInfo.variant != VariantXiangqi || board[rt][ft] != EmptySquare )
1414 *outp++ = 'x'; /* [HGM] Xiangqi has sideway noncaptures across river! */
1418 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1420 /* Use promotion suffix style "=Q" */
1422 if (appData.debugMode)
1423 fprintf(debugFP, "movetype=%d, promochar=%d=%c\n", (int)kind, promoChar, promoChar >= ' ' ? promoChar : '-');
1424 if (promoChar != NULLCHAR) {
1425 if(gameInfo.variant == VariantShogi) {
1426 /* [HGM] ... but not in Shogi! */
1427 *outp++ = promoChar == '=' ? '=' : '+';
1430 *outp++ = ToUpper(promoChar);
1439 /* Fabien moved code: FRC castling first (if KxR), wild castling second */
1440 /* Code added by Tord: FRC castling. */
1441 if((piece == WhiteKing && board[rt][ft] == WhiteRook) ||
1442 (piece == BlackKing && board[rt][ft] == BlackRook)) {
1444 safeStrCpy(out, "O-O", MOVE_LEN);
1446 safeStrCpy(out, "O-O-O", MOVE_LEN);
1447 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1449 /* End of code added by Tord */
1450 /* Test for castling or ICS wild castling */
1451 /* Use style "O-O" (oh-oh) for PGN compatibility */
1452 else if (rf == rt &&
1453 rf == ((piece == WhiteKing) ? 0 : BOARD_HEIGHT-1) &&
1454 (ft - ff > 1 || ff - ft > 1) && // No castling if legal King move (on narrow boards!)
1455 ((ff == BOARD_WIDTH>>1 && (ft == BOARD_LEFT+2 || ft == BOARD_RGHT-2)) ||
1456 (ff == (BOARD_WIDTH-1)>>1 && (ft == BOARD_LEFT+1 || ft == BOARD_RGHT-3)))) {
1457 if(ft==BOARD_LEFT+1 || ft==BOARD_RGHT-2)
1458 safeStrCpy(out, "O-O", MOVE_LEN);
1460 safeStrCpy(out, "O-O-O", MOVE_LEN);
1462 /* This notation is always unambiguous, unless there are
1463 kings on both the d and e files, with "wild castling"
1464 possible for the king on the d file and normal castling
1465 possible for the other. ICS rules for wild 9
1466 effectively make castling illegal for either king in
1467 this situation. So I am not going to worry about it;
1468 I'll just generate an ambiguous O-O in this case.
1470 return LegalityTest(board, flags, rf, ff, rt, ft, promoChar);
1473 /* else fall through */
1481 cl.kind = IllegalMove;
1482 cl.rank = cl.file = cl.either = 0;
1483 GenLegal(board, flags, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1485 if (cl.kind == IllegalMove && !(flags&F_IGNORE_CHECK)) {
1486 /* Generate pretty moves for moving into check, but
1487 still return IllegalMove.
1489 GenLegal(board, flags|F_IGNORE_CHECK, CoordsToAlgebraicCallback, (VOIDSTAR) &cl);
1490 if (cl.kind == IllegalMove) break;
1491 cl.kind = IllegalMove;
1494 /* Style is "Nf3" or "Nxf7" if this is unambiguous,
1495 else "Ngf3" or "Ngxf7",
1496 else "N1f3" or "N5xf7",
1497 else "Ng1f3" or "Ng5xf7".
1499 c = PieceToChar(piece) ;
1500 if( c == '~' || c == '+') {
1501 /* [HGM] print nonexistent piece as its demoted version */
1502 piece = (ChessSquare) (DEMOTED piece);
1504 if(c=='+') *outp++ = c;
1505 *outp++ = ToUpper(PieceToChar(piece));
1507 if (cl.file || (cl.either && !cl.rank)) {
1513 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1516 if(board[rt][ft] != EmptySquare)
1522 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1523 if (gameInfo.variant == VariantShogi) {
1524 /* [HGM] in Shogi non-pawns can promote */
1525 *outp++ = promoChar; // Don't bother to correct move type, return value is never used!
1530 /* [HGM] Always long notation for fairies we don't know */
1535 case WhiteGrasshopper:
1536 case BlackGrasshopper:
1538 /* Moving a nonexistent piece */
1542 /* Not a legal move, even ignoring check.
1543 If there was a piece on the from square,
1544 use style "Ng1g3" or "Ng1xe8";
1545 if there was a pawn or nothing (!),
1546 use style "g1g3" or "g1xe8". Use "x"
1547 if a piece was on the to square, even
1548 a piece of the same color.
1551 if (piece != EmptySquare && piece != WhitePawn && piece != BlackPawn) {
1552 *outp++ = ToUpper(PieceToChar(piece));
1557 else { *outp++ = (rf+ONE-'0')/10 + '0';*outp++ = (rf+ONE-'0')%10 + '0'; }
1558 if (board[rt][ft] != EmptySquare) *outp++ = 'x';
1562 else { *outp++ = (rt+ONE-'0')/10 + '0';*outp++ = (rt+ONE-'0')%10 + '0'; }
1563 /* Use promotion suffix style "=Q" */
1564 if (promoChar != NULLCHAR && promoChar != 'x') {
1566 *outp++ = ToUpper(promoChar);
1573 // [HGM] XQ: the following code serves to detect perpetual chasing (Asian rules)
1582 // I guess the following variables logically belong in the closure too, but I was too lazy and used globals
1584 int preyStackPointer, chaseStackPointer;
1587 char rf, ff, rt, ft;
1597 // there are three new callbacks for use with GenLegal: for adding captures, deleting them, and finding a recapture
1599 extern void AtacksCallback P((Board board, int flags, ChessMove kind,
1600 int rf, int ff, int rt, int ft,
1603 void AttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1609 { // For adding captures that can lead to chase indictment to the chaseStack
1610 if(board[rt][ft] == EmptySquare) return; // non-capture
1611 if(board[rt][ft] == WhitePawn && rt < BOARD_HEIGHT/2) return; // Pawn before river can be chased
1612 if(board[rt][ft] == BlackPawn && rt >= BOARD_HEIGHT/2) return; // Pawn before river can be chased
1613 if(board[rf][ff] == WhitePawn || board[rf][ff] == BlackPawn) return; // Pawns are allowed to chase
1614 if(board[rf][ff] == WhiteWazir || board[rf][ff] == BlackWazir) return; // King is allowed to chase
1615 // move cannot be excluded from being a chase trivially (based on attacker and victim); save it on chaseStack
1616 chaseStack[chaseStackPointer].rf = rf;
1617 chaseStack[chaseStackPointer].ff = ff;
1618 chaseStack[chaseStackPointer].rt = rt;
1619 chaseStack[chaseStackPointer].ft = ft;
1620 chaseStackPointer++;
1623 extern void ExistingAtacksCallback P((Board board, int flags, ChessMove kind,
1624 int rf, int ff, int rt, int ft,
1627 void ExistingAttacksCallback(board, flags, kind, rf, ff, rt, ft, closure)
1633 { // for removing pre-exsting captures from the chaseStack, to be left with newly created ones
1635 register ChaseClosure *cl = (ChaseClosure *) closure; //closure tells us the move played in the repeat loop
1637 if(board[rt][ft] == EmptySquare) return; // no capture
1638 if(rf == cl->rf && ff == cl->ff) { // attacks with same piece from new position are not considered new
1639 rf = cl->rt; ff = cl->ft; // doctor their fromSquare so they will be recognized in chaseStack
1641 // search move in chaseStack, and delete it if it occurred there (as we know now it is not a new capture)
1642 for(i=0; i<chaseStackPointer; i++) {
1643 if(chaseStack[i].rf == rf && chaseStack[i].ff == ff &&
1644 chaseStack[i].rt == rt && chaseStack[i].ft == ft ) {
1645 // move found on chaseStack, delete it by overwriting with move popped from top of chaseStack
1646 chaseStack[i] = chaseStack[--chaseStackPointer];
1652 extern void ProtectedCallback P((Board board, int flags, ChessMove kind,
1653 int rf, int ff, int rt, int ft,
1656 void ProtectedCallback(board, flags, kind, rf, ff, rt, ft, closure)
1662 { // for determining if a piece (given through the closure) is protected
1663 register ChaseClosure *cl = (ChaseClosure *) closure; // closure tells us where to recapture
1665 if(rt == cl->rt && ft == cl->ft) cl->recaptures++; // count legal recaptures to this square
1666 if(appData.debugMode && board[rt][ft] != EmptySquare)
1667 fprintf(debugFP, "try %c%c%c%c=%d\n", ff+AAA, rf+ONE,ft+AAA, rt+ONE, cl->recaptures);
1670 extern char moveList[MAX_MOVES][MOVE_LEN];
1672 int PerpetualChase(int first, int last)
1673 { // this routine detects if the side to move in the 'first' position is perpetually chasing (when not checking)
1676 ChessSquare captured;
1678 preyStackPointer = 0; // clear stack of chased pieces
1679 for(i=first; i<last; i+=2) { // for all positions with same side to move
1680 if(appData.debugMode) fprintf(debugFP, "judge position %i\n", i);
1681 chaseStackPointer = 0; // clear stack that is going to hold possible chases
1682 // determine all captures possible after the move, and put them on chaseStack
1683 GenLegal(boards[i+1], PosFlags(i), AttacksCallback, &cl);
1684 if(appData.debugMode) { int n;
1685 for(n=0; n<chaseStackPointer; n++)
1686 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1687 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1688 fprintf(debugFP, ": all capts\n");
1690 // determine all captures possible before the move, and delete them from chaseStack
1691 cl.rf = moveList[i][1]-ONE; // prepare closure to pass move that led from i to i+1
1692 cl.ff = moveList[i][0]-AAA+BOARD_LEFT;
1693 cl.rt = moveList[i][3]-ONE;
1694 cl.ft = moveList[i][2]-AAA+BOARD_LEFT;
1695 GenLegal(boards[i], PosFlags(i), ExistingAttacksCallback, &cl);
1696 if(appData.debugMode) { int n;
1697 for(n=0; n<chaseStackPointer; n++)
1698 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1699 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1700 fprintf(debugFP, ": new capts after %c%c%c%c\n", cl.ff+AAA, cl.rf+ONE, cl.ft+AAA, cl.rt+ONE);
1702 // chaseSack now contains all captures made possible by the move
1703 for(j=0; j<chaseStackPointer; j++) { // run through chaseStack to identify true chases
1704 int attacker = (int)boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1705 int victim = (int)boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1707 if(attacker >= (int) BlackPawn) attacker = BLACK_TO_WHITE attacker; // convert to white, as piecee type
1708 if(victim >= (int) BlackPawn) victim = BLACK_TO_WHITE victim;
1710 if((attacker == WhiteKnight || attacker == WhiteCannon) && victim == WhiteRook)
1711 continue; // C or H attack on R is always chase; leave on chaseStack
1713 if(attacker == victim) {
1714 if(LegalityTest(boards[i+1], PosFlags(i+1), chaseStack[j].rt,
1715 chaseStack[j].ft, chaseStack[j].rf, chaseStack[j].ff, NULLCHAR) == NormalMove) {
1716 // we can capture back with equal piece, so this is no chase but a sacrifice
1717 chaseStack[j] = chaseStack[--chaseStackPointer]; // delete the capture from the chaseStack
1718 j--; /* ! */ continue;
1723 // the attack is on a lower piece, or on a pinned or blocked equal one
1724 // test if the victim is protected by a true protector. First make the capture.
1725 captured = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1726 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = boards[i+1][chaseStack[j].rf][chaseStack[j].ff];
1727 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = EmptySquare;
1728 // Then test if the opponent can recapture
1729 cl.recaptures = 0; // prepare closure to pass recapture square and count moves to it
1730 cl.rt = chaseStack[j].rt;
1731 cl.ft = chaseStack[j].ft;
1732 if(appData.debugMode) {
1733 fprintf(debugFP, "test if we can recapture %c%c\n", cl.ft+AAA, cl.rt+ONE);
1735 GenLegal(boards[i+1], PosFlags(i+1), ProtectedCallback, &cl); // try all moves
1736 // unmake the capture
1737 boards[i+1][chaseStack[j].rf][chaseStack[j].ff] = boards[i+1][chaseStack[j].rt][chaseStack[j].ft];
1738 boards[i+1][chaseStack[j].rt][chaseStack[j].ft] = captured;
1739 // if a recapture was found, piece is protected, and we are not chasing it.
1740 if(cl.recaptures) { // attacked piece was defended by true protector, no chase
1741 chaseStack[j] = chaseStack[--chaseStackPointer]; // so delete from chaseStack
1745 // chaseStack now contains all moves that chased
1746 if(appData.debugMode) { int n;
1747 for(n=0; n<chaseStackPointer; n++)
1748 fprintf(debugFP, "%c%c%c%c ", chaseStack[n].ff+AAA, chaseStack[n].rf+ONE,
1749 chaseStack[n].ft+AAA, chaseStack[n].rt+ONE);
1750 fprintf(debugFP, ": chases\n");
1752 if(i == first) { // copy all people chased by first move of repeat cycle to preyStack
1753 for(j=0; j<chaseStackPointer; j++) {
1754 preyStack[j].rank = chaseStack[j].rt;
1755 preyStack[j].file = chaseStack[j].ft;
1757 preyStackPointer = chaseStackPointer;
1760 for(j=0; j<chaseStackPointer; j++) {
1761 for(k=0; k<preyStackPointer; k++) {
1762 // search the victim of each chase move on the preyStack (first occurrence)
1763 if(chaseStack[j].ft == preyStack[k].file && chaseStack[j].rt == preyStack[k].rank ) {
1764 if(k < tail) break; // piece was already identified as still being chased
1765 preyStack[preyStackPointer] = preyStack[tail]; // move chased piece to bottom part of preyStack
1766 preyStack[tail] = preyStack[k]; // by swapping
1767 preyStack[k] = preyStack[preyStackPointer];
1773 preyStackPointer = tail; // keep bottom part of preyStack, popping pieces unchased on move i.
1774 if(appData.debugMode) { int n;
1775 for(n=0; n<preyStackPointer; n++)
1776 fprintf(debugFP, "%c%c ", preyStack[n].file+AAA, preyStack[n].rank+ONE);
1777 fprintf(debugFP, "always chased upto ply %d\n", i);
1779 // now adjust the location of the chased pieces according to opponent move
1780 for(j=0; j<preyStackPointer; j++) {
1781 if(preyStack[j].rank == moveList[i+1][1]-ONE &&
1782 preyStack[j].file == moveList[i+1][0]-AAA+BOARD_LEFT) {
1783 preyStack[j].rank = moveList[i+1][3]-ONE;
1784 preyStack[j].file = moveList[i+1][2]-AAA+BOARD_LEFT;
1789 return preyStackPointer; // if any piece was left on preyStack, it has been perpetually chased